Jumbo Frame's



  • OK so just a general inquiry as I’m doing some testing and want to make sure it works.

    So just tested and confirmed this, that enabling JUMBO Frames to 8000 does allow me to increase my throughput up to 3.57 - 4 GB per minute.

    Is there anything else that I can do to get closer to 10GB/MIN?

    What do you guys recommend.

    This is built on a private network, I can do some testing here.



  • the default size for jumbo frames is 9000. So you send 1/6th the number of packets, less headers and tail relative to the amount of data being sent. The real saving is the time it takes to get on the cable, as you’re transmitting a 1/6 of the number of frames for the same data, you save on the time to transmit. you also do 1/6th the number of mac checks, so it lowers CPU usage, unless you have a TCPIP off load card.

    Always enable it with iSCSI, but check the “path” all support jumbo frames.

    Hope it helps



  • Hi,

    I’ve been experiencing a bit, and it turns out most of my hosts can’t do jumbo frames. But since iPXE & FOG use DHCP in a reasonnably standard way, pushing the MTU using DHCP (and having switches that support it, obviously) should have the client use it. But it requires the hardware of the NICs to support it, and the driver as well…

    For those who don’t know what Jumbo Frames are, it’s a way to increase the maximum size (in fact, [URL=‘https://en.wikipedia.org/wiki/Maximum_transmission_unit’]MTU[/URL] means Maximum Transmission Unit) of the IP packet used on the network. The standard value is 1500, which means each TCP or UDP packet has to be sliced in 1500 bytes parts, adding a lot of overhead for huge transfers. Thus, putting that value to 9000 (the “jumbo” size), you avoid resending a full tcp/udp header every 1500 bytes…



  • I know a switch can have it’s “envelop pushed” a bit, but am curious as to how.

    Anyways on a side note we’re finally getting started with that Promise device and will be testing with that on our private network soon enough.

    :)

    Now if only I can get the boss to spring for some new equipment rather than the make it work equipment I’ve been using ;)


  • Senior Developer

    The fastest the connection between the 10 gig and gig switches could ever reach would be 1 gig.

    The jumbo frame thing I’m not familiar with so I’m not much help in this posting. Sorry.


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